Bob Majdak has a quick new post to his site showing you how to log messages to Apache using a JSON format instead of the usual single-line information.
So this past week I have been doing a lot of logging, parsing, and graphing. I was sitting there wondering what I could do to make the Apache access logs easier to work with. Then it hit me, a brilliant stroke of win: why not format it in JSON? Then in my log parser I could just json_decode it! As far as I know there are no tricks to make Apache do this for you, so really all we have to do is define a custom log format that happens to look like JSON.
He includes the "LogFormat" line you'll need to add to your Apache configuration to make it log the JSON and a bit of PHP to help you pull in the file's contents and parse each line.